I know someone who works for the UK Grid. Apparently home solar is problematic due to rapid swings. E.g. a cloud rolls over and suddenly demand spikes without much warning. As it clears, you get a surge of power back into the grid. Unfortunately, the grid was designed for a top down approach. Rapid surges of backfed power can destabilise it.

It's something that is being fixed slowly, but prying enough money loose for the upgrades is a challenge.

Balcony solar was also initially illegal due to the backfed being dangerous to linesmen. That has now been solved, but inertia is still a political problem.

And just to clarify, I'm all for renewables as fast as we can deploy them. My issue is with the grids not being updated, not with people getting solar etc.